Abstract:

A magneto-resistance effect element comprises: a magneto-resistance effect
stack including an upper magnetic layer and a lower magnetic layer whose
magnetization directions change in accordance with an external magnetic
field, a non-magnetic intermediate layer sandwiched between the upper and
lower magnetic layers; an upper shield electrode layer and a lower shield
electrode layer which are provided to sandwich the magneto-resistance
effect stack therebetween in the direction of stacking the
magneto-resistance effect stack, wherein the upper shield electrode layer
and the lower shield electrode layer supply sense current in the
direction of stacking, and magnetically shield the magneto-resistance
effect stack; a first bias magnetic layer which is provided on a surface
of the magneto-resistance effect stack opposite to an air bearing
surface, and wherein the first bias magnetic layer is magnetized in a
direction perpendicular to said air bearing surface; and a pair of second
bias magnetic layers provided on respective both sides of said
magneto-resistance effect stack in a track width direction, and wherein
the second bias magnetic layers are magnetized in a direction
substantially parallel to said track width direction; wherein the
magnetic pole on a surface of one of said second bias magnetic layers
which faces said magneto-resistance effect stack has the same polarity as
the magnetic pole on a surface of the other of said second bias magnetic
layers which faces said magneto-resistance effect stack, and has a
polarity different from the polarity of the magnetic pole on a surface of
said first bias magnetic layer which faces said magneto-resistance effect
stack.

Claims:

1. A magneto-resistance effect element comprising:a magneto-resistance
effect stack including an upper magnetic layer and a lower magnetic layer
whose magnetization directions change in accordance with an external
magnetic field, a non-magnetic intermediate layer sandwiched between the
upper and lower magnetic layers;an upper shield electrode layer and a
lower shield electrode layer which are provided to sandwich the
magneto-resistance effect stack therebetween in the direction of stacking
the magneto-resistance effect stack, wherein the upper shield electrode
layer and the lower shield electrode layer supply sense current in the
direction of stacking, and magnetically shield the magneto-resistance
effect stack;a first bias magnetic layer which is provided on a surface
of the magneto-resistance effect stack opposite to an air bearing
surface, and wherein the first bias magnetic layer is magnetized in a
direction perpendicular to said air bearing surface; anda pair of second
bias magnetic layers provided on respective both sides of said
magneto-resistance effect stack in a track width direction, and wherein
the second bias magnetic layers are magnetized in a direction
substantially parallel to said track width direction;wherein the magnetic
pole on a surface of one of said second bias magnetic layers which faces
said magneto-resistance effect stack has the same polarity as the
magnetic pole on a surface of the other of said second bias magnetic
layers which faces said magneto-resistance effect stack, and has a
polarity different from the polarity of the magnetic pole on a surface of
said first bias magnetic layer which faces said magneto-resistance effect
stack.

2. The magneto-resistance effect element according to claim 1, wherein
each of said second bias magnetic layers comprises:a ferromagnetic layer;
andan antiferromagnetic layer exchange-coupled to said ferromagnetic
layer.

3. The magneto-resistance effect element according to claim 1, wherein
each of said second bias magnetic layers comprises a soft magnetic layer.

4. The magneto-resistance effect element according to claim 1, wherein
said first bias magnetic layer extends toward said magneto-resistance
effect stack while a width thereof in the track width direction
decreases.

5. The magneto-resistance effect element according to claim 1, wherein
said first bias magnetic layer is shaped as a substantially isosceles
trapezoid within a stacked plane of said magneto-resistance effect
stack;said isosceles trapezoid has two parallel sides, one of which is
shorter than the other and the shorter side is disposed to be closer to
said magneto-resistance effect stack.

6. The magneto-resistance effect element according to claim 1, wherein
said first bias magnetic layer is shaped as a substantially isosceles
trapezoid within a stacked plane of said magneto-resistance effect
stack;said isosceles trapezoid has two parallel sides, one of which is
shorter than the other and the shorter side is disposed to be closer to
said magneto-resistance effect stack; andsaid shorter side has a width
which is twice the width of said magneto-resistance effect stack in the
track width direction or less.

7. The magneto-resistance effect element according to claim 1, wherein
said first bias magnetic layer is shaped as a substantially isosceles
trapezoid within a stacked plane of said magneto-resistance effect
stack;said isosceles trapezoid has two parallel sides, one of which is
shorter than the other and the shorter side is disposed to be closer to
said magneto-resistance effect stack; andsaid shorter side has a width
which is substantially equal to the width of said magneto-resistance
effect stack in the track width direction or less.

8. The magneto-resistance effect element according to claim 1, wherein
said first bias magnetic layer is shaped as a substantially isosceles
trapezoid within a stacked plane of said magneto-resistance effect
stack;said isosceles trapezoid has two parallel sides, one of which is
shorter than the other and the shorter side is disposed to be closer to
said magneto-resistance effect stack; andsaid isosceles trapezoid has an
exterior angle in a range from 40 degrees to 80 degrees at both ends of
the shorter side.

9. The magneto-resistance effect element according to claim 1, wherein
said first bias magnetic layer is shaped as a substantially isosceles
trapezoid within a stacked plane of said magneto-resistance effect
stack;said isosceles trapezoid has two parallel sides, one of which is
shorter than the other and the shorter side is disposed to be closer to
said magneto-resistance effect stack; andsaid isosceles trapezoid has an
exterior angle of about 60 degrees at both ends of the shorter side.

10. The magneto-resistance effect element according to claim 1, wherein
said non-magnetic intermediate layer is made of copper and has a film
thickness of about 1.3 nm.

11. The magneto-resistance effect element according to claim 1, further
comprising:an insulating film disposed between said magneto-resistance
effect stack and said first bias magnetic layer, and between said
magneto-resistance effect stack and second bias magnetic layers.

12. The magneto-resistance effect element according to claim 1, further
comprising:non-magnetic layers disposed on the both sides of said first
bias magnetic layer in the track width direction.

13. A slider including the magneto-resistance effect element according to
claim 1.

14. A wafer having a magneto-resistance effect stack that is to be formed
into the magneto-resistance effect element according to claim 1.

15. A head gimbal assembly including the slider according to claim 13, and
a suspension for resiliently supporting the slider.

16. A hard disk drive including the slider according to claim 13, and a
device for supporting the slider and positioning the slider with respect
to a recording medium.

17. A method of manufacturing a magneto-resistance effect element,
comprising:a magneto-resistance effect stack forming step of forming a
lower magnetic layer whose magnetization direction changes in accordance
with an external magnetic field, a non-magnetic intermediate layer, and
an upper magnetic layer whose magnetization direction changes in
accordance with an external magnetic field, successively upwardly in the
order named in a direction of stacking, on a lower shield electrode
layer;a second bias magnetic layer forming step of removing both sides of
said magneto-resistance effect stack in a track width direction, and
filling removed spaces with a pair of second bias magnetic layers
respectively therein;a first bias magnetic layer forming step of forming
a recess in a surface opposite to a surface to be formed into an air
bearing surface of said magneto-resistance effect stack, wherein said
recess extends toward said magneto-resistance effect stack while a width
thereof in the track width direction decreases, and filling a portion of
said recess with a first bias magnetic layer;a magnetization direction
securing step of securing magnetization directions of said second bias
magnetic layers substantially parallel to said track width direction,
such that the magnetic pole on a surface of one of said second bias
magnetic layers which faces said magneto-resistance effect stack has the
same polarity as the magnetic pole on a surface of the other of said
second bias magnetic layers which faces said magneto-resistance effect
stack, and has a polarity different from the polarity of the magnetic
pole on a surface of said first bias magnetic layer which faces said
magneto-resistance effect stack; andan upper shield electrode layer
forming step of forming an upper shield electrode layer on said
magneto-resistance effect stack, said first bias magnetic layer, and said
second bias magnetic layers.

18. The method of manufacturing a magneto-resistance effect element
according to claim 17, further comprising:a non-magnetic layer forming
step of removing respective both sides of a region to be formed into said
first bias magnetic layer in a track width direction, and filling removed
spaces with a non-magnetic layer.

19. The method of manufacturing a magneto-resistance effect element
according to claim 17, wherein each of said first bias magnetic layers
comprises:a ferromagnetic layer; andan antiferromagnetic layer
exchange-coupled to said ferromagnetic layer; andwherein said
magnetization direction securing step comprises the step of, after said
first bias magnetic layer forming step, annealing said MR stack to a
temperature equal to or higher than a blocking temperature of said
antiferromagnetic layer, within a magnetic field emitted from said first
bias magnetic layer.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to a magneto-resistance effect element
and a method of manufacturing same, and more particularly to the element
structure of a magneto-resistance effect element having dual free layers.

[0003]2. Description of the Related Art

[0004]Thin-film magnetic heads used in hard disk drives are constructed
from a readout head having a reproducing element for reading and a write
head having an inductive-type electromagnetic conversion device for
writing. A giant magneto-resistance (GMR) element is known as the
reproducing element of the thin film magnetic head. Conventionally, CIP
(Current In Plane) GMR elements in which a sense current flows in a
direction parallel to the film surface have been mainly used. Recently,
however, in order to support ever higher recording densities, CPP
(Current Perpendicular to the Plane) type elements in which the sense
current flows in a direction perpendicular to the film surface have been
developed. Known examples of this type of element include TMR (Tunnel
Magneto-resistance) elements utilizing TMR effects and CPP-GMR elements
utilizing GMR effects.

[0005]CPP elements include a magneto-resistance effect (MR) stack having a
magnetic layer (free layer) in which the magnetization direction changes
according to an external magnetic field, a magnetic layer (pinned layer)
in which the magnetization direction is fixed, and a non-magnetic
intermediate layer which is sandwiched between the pinned layer and the
free layer. To fix the magnetization direction in the pinned layer, the
MR stack is provided with an anti-ferromagnetic layer (pinning layer).
The pinning layer is provided adjacent to the pinned layer, and fix the
magnetization direction of the pinned layer by exchange coupling with the
pinned layer. The MR stack may also be called a spin valve film.

[0006]Bias magnetic layers for applying a bias magnetic field to the free
layer are provided on both sides of the spin-valve film in a track width
direction. The bias magnetic layers apply a bias magnetic-field to the
free layer in a direction parallel to the track width direction. In an
Initial magnetization state (the state in which only a bias magnetic
field is applied), the free layer is magnetized in a direction
perpendicular to the magnetization direction of the pinned layer. The
free layer is turned into a single magnetic domain by the bias magnetic
field emitted from the bias magnetic layers. This provides an improvement
in linearity of a change in resistance with respect to a change in an
external magnetic field and an effective reduction in Barkhausen noise. A
relative angle between the magnetization direction of the free layer and
the magnetization direction of the pinned layer changes in accordance
with an external magnetic field, and as a result, electric resistance of
sense current that flows in a direction perpendicular to the film surface
of the spin-valve film is changed. The external magnetic field is
detected based on the above property. The spin-valve film is magnetically
shielded by shield layers on both sides thereof with regard to the
direction of stacking. The stacked direction of the spin-valve film is
aligned with the circumferential direction of the recording medium when a
thin-film magnetic head is assembled in the hard disk drive. Therefore,
the shield layers have a role of shielding a magnetic field emitted from
adjacent bits on the same track of the recording medium.

[0007]In recent years, higher recording density is desired. However, an
improvement in recording density requires an improvement in track
recording density, which requires a reduction in spacing between upper
and lower shield layers (a gap between shields). In order to achieve
this, a decrease in thickness of the spin-valve film is required.
However, there is large limitation that originates from the layer
structure in the conventional CPP elements. Specifically, since the
pinned layer requires that the magnetization direction be firmly fixed
without being influenced by an external magnetic field, a so-called
synthetic pinned layer is usually used. The synthetic pinned layer
includes an outer pinned layer, an inner pinned layer, and a non-magnetic
intermediate layer which consists of Ru or Rh and which is sandwiched
between the outer pinned layer and the inner pinned layer. Moreover, an
antiferromagnetic layer is provided in contact with the outer pinned
layer in order to fix the magnetization direction of the outer pinned
layer. The antiferromagnetic layer typically consists of IrMn. In the
synthetic pinned layer, the antiferromagnetic layer is coupled to the
outer pinned layer via exchange-coupling so that the magnetization
direction of the outer pinned layer is fixed. The inner pinned layer is
antiferromagnetically coupled to the outer pinned layer via the
non-magnetic intermediate layer so that the magnetization direction of
the inner pinned layer is fixed. Since the magnetization directions of
the inner pinned layer and the outer pinned layer are anti-parallel to
each other, magnetization of the pinned layer is limited as a whole.
Despite such a merit of the synthetic pinned layer, however, a large
number of layers are required to constitute a CPP element that includes
the synthetic pinned layer. This imposes limitation on a reduction in the
thickness of the spin-valve film.

[0008]Meanwhile, a novel layer structure that is entirely different from
that of the above-mentioned conventional spin-valve film has been
proposed in recent years. Specifically, "Current-in-Plane GMR Tri-layer
Head Design for Hard-Disk Drives" (IEEE TRANSACTIONS ON MAGNETICS, Vol.
43, No. 2, February 2007) discloses, for a CIP element, an MR stack that
includes a upper and lower magnetic layers in which the magnetization
directions change according to the external magnetic field, and a
non-magnetic intermediate layer sandwiched between the upper magnetic
layer and the lower magnetic layer. Since the magnetization directions of
the upper and lower magnetic layers change according to the external
magnetic field, these layers may also be called free layers. A bias
magnetic layer is provided on a side of the MR stack opposite to an air
bearing surface, and a bias magnetic field is applied in a direction that
is perpendicular to the air bearing surface. The magnetization directions
of the upper and lower magnetic layers adopt a certain relative angle
because of the magnetic field applied from the bias magnetic layer. If an
external magnetic field is applied in this state, then the magnetization
directions of the upper and lower magnetic layers are changed. As a
result, the relative angle between the magnetization direction of the
upper magnetic layer and the magnetization direction of the lower
magnetic layer is changed, and accordingly, electric resistance of sense
current is changed. It is possible to detect the external magnetization
based on this property. U.S. Pat. No. 7,035,062 discloses an example in
which such a layer structure is applied to a CPP element. Such a layer
structure using the pair of free layers has a potential for facilitating
a reduction in gap between the shields, because it does not require the
conventional synthetic pinned layer and the antiferromagnetic layer,
allowing a simplified layer structure.

[0009]However, the magneto-resistance effect (MR) element with the pair of
free layers has the following problems: As the film thickness of the MR
stack is reduced, the film thickness of the bias magnetic layer is also
reduced. Unlike the configuration according to the related art, the bias
magnetic layer is provided only on the side of the MR stack which is
opposite to the air bearing surface. Accordingly, the bias magnetic field
emitted from the bias magnetic layer is liable to be dispersed, and
cannot efficiently be applied to the upper and lower magnetic layers as
the free layers. For these reasons, it is difficult for the bias magnetic
field to maintain a magnetic field intensity level strong enough to turn
the upper and lower magnetic layers into a single magnetic domain.

SUMMARY OF THE INVENTION

[0010]The present invention is directed to a CPP type magneto-resistance
effect element of a layer structure including a magneto-resistance effect
stack having a pair of free layers, and provided with bias magnetic
layers. It is an object of the present invention to provide a
magneto-resistance effect element with the above layer structure which
will have a reduced gap between the shields for higher recording density
and which will produce an increased bias magnetic field for increased
magnetic field detection sensitivity. Another object of the present
invention is to provide a method of manufacturing such a
magneto-resistance effect element.

[0011]According to an embodiment of the present invention, a
magneto-resistance effect element comprising: a magneto-resistance effect
stack including an upper magnetic layer and a lower magnetic layer whose
magnetization directions change in accordance with an external magnetic
field, a non-magnetic intermediate layer sandwiched between the upper and
lower magnetic layers; an upper shield electrode layer and a lower shield
electrode layer which are provided to sandwich the magneto-resistance
effect stack therebetween in the direction of stacking the
magneto-resistance effect stack, wherein the upper shield electrode layer
and the lower shield electrode layer supply sense current in the
direction of stacking, and magnetically shield the magneto-resistance
effect stack; a first bias magnetic layer which is provided on a surface
of the magneto-resistance effect stack opposite to an air bearing
surface, and wherein the first bias magnetic layer is magnetized in a
direction perpendicular to said air bearing surface; and a pair of second
bias magnetic layers provided on respective both sides of said
magneto-resistance effect stack in a track width direction, and wherein
the second bias magnetic layers are magnetized in a direction
substantially parallel to said track width direction; wherein the
magnetic pole on a surface of one of said second bias magnetic layers
which faces said magneto-resistance effect stack has the same polarity as
the magnetic pole on a surface of the other of said second bias magnetic
layers which faces said magneto-resistance effect stack, and has a
polarity different from the polarity of the magnetic pole on a surface of
said first bias magnetic layer which faces said magneto-resistance effect
stack.

[0012]In accordance with this structure, the need for providing a pinning
layer and a synthetic pinned layer in the magneto-resistance stack is
obviated, and a reduction in the magneto-resistance stack thickness is
facilitated. Therefore, a reduction in the gap between the shields can be
achieved. Since second bias magnetic layers are formed on both sides of
the magneto-resistance stack, a strong bias magnetic field is applied to
the upper and lower magnetic layers as free layers. Thus, the
magnetization direction of the upper magnetic layer and the magnetization
direction of the lower magnetic layer are substantially perpendicular to
each other. In this way, it is possible to increase the detection
sensitivity of the magneto-resistance effect element and to provide a
magneto-resistance effect element that can easily cope with high
recording density.

[0013]According to another embodiment of the present invention, a method
of manufacturing a magneto-resistance effect element, comprising: a
magneto-resistance effect stack forming step of forming a lower magnetic
layer whose magnetization direction changes in accordance with an
external magnetic field, a non-magnetic intermediate layer, and an upper
magnetic layer whose magnetization direction changes in accordance with
an external magnetic field, successively upwardly in the order named in a
direction of stacking, on a lower shield electrode layer; a second bias
magnetic layer forming step of removing both sides of said
magneto-resistance effect stack in a track width direction, and filling
removed spaces with a pair of second bias magnetic layers respectively
therein; a first bias magnetic layer forming step of forming a recess in
a surface opposite to a surface to be formed into an air bearing surface
of said magneto-resistance effect stack, wherein said recess extends
toward said magneto-resistance effect stack while a width thereof in the
track width direction decreases, and filling a portion of said recess
with a first bias magnetic layer; a magnetization direction securing step
of securing magnetization directions of said second bias magnetic layers
substantially parallel to said track width direction, such that the
magnetic pole on a surface of one of said second bias magnetic layers
which faces said magneto-resistance effect stack has the same polarity as
the magnetic pole on a surface of the other of said second bias magnetic
layers which faces said magneto-resistance effect stack, and has a
polarity different from the polarity of the magnetic pole on a surface of
said first bias magnetic layer which faces said magneto-resistance effect
stack; and an upper shield electrode layer forming step of forming an
upper shield electrode layer on said magneto-resistance effect stack,
said first bias magnetic layer, and said second bias magnetic layers.

[0014]The above and other objects, features and advantages of the present
invention will become apparent from the following description with
reference to the accompanying drawings which illustrate examples of the
present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view of a magneto-resistance effect element
according to an embodiment of the present invention;

[0016]FIG. 2A is a side view of the magneto-resistance effect element when
viewed from 2A-2A direction of FIG. 1;

[0017]FIG. 2B is a cross-sectional view of the magneto-resistance effect
element along 2B-2B line of FIG. 1;

[0019]FIG. 3 is a view showing the directions of bias magnetic fields
applied from first and second bias magnetic layers;

[0020]FIG. 4 is a conceptual view showing an operation principle of the
magneto-resistance effect element shown in FIG. 1;

[0021]FIG. 5A is a diagram showing the magnetization direction of an upper
magnetic layer in the absence of a bias magnetic field;

[0022]FIG. 5B is a diagram showing the magnetization direction of a lower
magnetic layer in the absence of a bias magnetic field;

[0023]FIG. 6A is a diagram showing the magnetization direction of the
upper magnetic layer when only the bias magnetic field from the first
bias magnetic layer is applied;

[0024]FIG. 6B is a diagram showing the magnetization direction of the
lower magnetic layer when only the bias magnetic field from the first
bias magnetic layer is applied;

[0025]FIG. 7A is a diagram showing the magnetization direction of the
upper magnetic layer when the bias magnetic fields from the first and
second bias magnetic layers are applied;

[0026]FIG. 7B is a diagram showing the magnetization direction of the
lower magnetic layer when the bias magnetic fields from the first and
second bias magnetic layers are applied;

[0027]FIG. 8 is a flowchart explaining a method of manufacturing the
magneto-resistance effect element shown in FIG. 1;

[0028]FIGS. 9A to 17C are step diagrams explaining the method of
manufacturing the magneto-resistance effect element shown in FIG. 1;

[0029]FIG. 18 is a graph showing the relationship between the width of a
tip end of the first bias magnetic layer and the output of the
magneto-resistance effect element;

[0030]FIG. 19 is a graph showing the relationship between the angle of the
tip end of the first bias magnetic layer and the output of the
magneto-resistance effect element;

[0031]FIGS. 20A and 20B are cross-sectional views of magneto-resistance
effect elements including first bias magnetic layer having different tip
end angle;

[0032]FIG. 21 is a cross-sectional view of a thin-film magnetic head taken
along a plane perpendicular to air bearing surface S;

[0033]FIG. 22 is a plan view of a wafer which is used to manufacture the
magneto-resistance effect element of the present invention;

[0034]FIG. 23 is a perspective view of a slider of the present invention;

[0035]FIG. 24 is a perspective view of a head arm assembly including a
head gimbal assembly which incorporates a slider of the present
invention;

[0036]FIG. 25 is a side view of a head arm assembly which incorporates
sliders of the present invention; and

[0037]FIG. 26 is a plan view of a hard disk drive which incorporates
sliders of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038]An embodiment of the present invention will now be described with
reference to the attached drawings. A magneto-resistance effect element
of the present embodiment is particularly suitable for use as the reading
device of a thin-film magnetic head in a hard-disk drive. FIG. 1 is a
perspective view of the magneto-resistance effect element according to
the embodiment of the present invention. FIG. 2A is a side view of the
magneto-resistance effect element when viewed from 2A-2A direction of
FIG. 1, i.e., viewed from an air bearing surface (a surface parallel to a
z-x plane in FIG. 1). FIG. 2B is a cross-sectional view of the
magneto-resistance effect element as viewed from a surface along 2B-2B
line of FIG. 1, i.e., a surface perpendicular to a track width direction
T (a surface parallel to a y-z plane in FIG. 1). FIG. 2C is a
cross-sectional view of the magneto-resistance effect element as viewed
from a surface along 2C-2C line of FIG. 2A, i.e., a surface along a film
surface of a magneto-resistance effect (MR) stack (a surface parallel to
an x-y plane in FIG. 1), or specifically as viewed from above in
direction of stacking P of the MR stack. The air bearing surface (ABS)
refers to a surface of magneto-resistance effect element 1 which faces
recording medium 21.

[0039]Magneto-resistance effect element 1 comprises MR stack 2, upper
shield electrode layer 3 and lower shield electrode layer 4 which are
provided such that they sandwich MR stack 2 in the direction of stacking
P, first bias magnetic layer 13 provided on the surface of stack 2 that
is opposite to air bearing surface S, and a pair of second bias magnetic
layers 17a, 17b provided respectively on both sides of MR stack 2 in
track width direction T.

[0040]MR stack 2 is sandwiched between upper shield electrode layer 3 and
lower shield electrode layer 4 with the tip end thereof exposed at air
bearing surface S. When a voltage is applied between upper shield
electrode layer 3 and lower shield electrode layer 4, sense current 22
flows through MR stack 2 in direction of stacking P, i.e., a direction
perpendicular to the film surfaces. Magnetic field of recording medium 21
at a position facing MR stack 2 changes in accordance with the movement
of recording medium 21 in moving direction 23 The change in magnetic
field is detected as a change in electric resistance which is caused by
the magneto-resistance effect. Based on this principle,
magneto-resistance effect element 1 reads magnetic information that is
recorded in each magnetic domain of recording medium 21.

[0041]Table 1 shows an example of the layer structure of MR stack 2. In
the table, the layers are shown in the order of stacking, from buffer
layer 5 in the bottom column, which is on the side of lower shield
electrode layer 4, toward cap layer 9 in the top column, which is on the
side of upper shield electrode layer 3. In Table 1, the numerical values
in the composition column represent atomic percentage of the elements. MR
stack 2 includes buffer layer 5, lower magnetic layer 6, non-magnetic
intermediate layer 7, upper magnetic layer 8, and cap layer 9, which are
successively stacked in the order named on lower shield electrode layer 4
which is made of an 80Ni20Fe layer having a thickness of about 1 μm.

[0042]Buffer layer 5 is provided as a seed layer for lower magnetic layer
6. Both lower magnetic layer 6 and upper magnetic layer 8, which have
layer configurations in which a NiFe layer is sandwiched by CoFe layers,
are free layers whose magnetization directions are changed in accordance
with an external magnetic field. A Cu layer is provided as non-magnetic
intermediate layer 7 between the pair of free layers. The Cu layer has a
film thickness of 1.3 nm. Cu exhibits the largest binding energy at this
thickness, allowing lower magnetic layer 6 and upper magnetic layer 8 to
be magnetically strongly coupled via antiferromagnetic coupling.

[0043]By providing the CoFe layers in lower magnetic layer 6 and in upper
magnetic layer 8, the spin polarization factor is increased at the
interfaces of the Cu layer as compared to the layer configuration in
which the Cu layer and the NiFe layer is in direct contact, and thus the
magnetic resistance effect is enhanced. Non-magnetic intermediate layer 7
may comprise a Ru layer instead of the Cu layer.

[0044]Either one or both of lower magnetic layer 6 and upper magnetic
layer 8 may comprise a single 70Co30Fe layer rather than the multi-layer
configuration shown in Table 1. Cap layer 9 is provided to prevent
deterioration of each layer. Upper shield electrode layer 3, which is
made of an 80Ni20Fe layer having a thickness of about 1 μm, is
provided on cap layer 9.

[0045]Upper shield electrode layer 3 and lower shield electrode layer 4
function as electrodes for supplying sense current 22 to MR stack 2 in
direction of stacking P (the direction perpendicular to the film
surfaces), and also function as shield layers for shielding against
magnetic field emitted from adjacent bits on the same track of recording
medium 21. Specifically, since direction of stacking P of MR stack 2
corresponds to the circumferential direction of recording medium 21 when
the thin film magnetic head is incorporated into a hard disc drive, a
magnetic field emitted from adjacent bits on the same track of recording
medium 21 is shielded by upper shield layer 3 and lower shield layer 4.

[0046]When magneto-resistance effect element 1 is viewed from recording
medium 21, as shown in FIG. 2A, MR stack 2 is surrounded by upper shield
electrode layer 3 and lower shield electrode layer 4. Thus, upper shield
electrode layer 3 and lower shield electrode layer 4 define gap G between
the shields of magneto-resistance effect element 1. Gap G between the
shields is determined by the film thickness of MR stack 2. In the
magneto-resistance effect element 1 of the present embodiment, since the
pinning layer and the outer pinned layer become unnecessary, a
significant reduction in thickness can be achieved as compared to the
spin-valve film of the conventional CPP element. Therefore, Gap G between
the shields is highly reduced.

[0047]First bias magnetic layer 13 is provided such that it faces the
surface of MR stack 2 that is opposite to air bearing surface S. First
bias magnetic layer 13 may be made of a CoPt layer having a thickness of
30 nm, for example. First bias magnetic layer 13 should preferably be
made of a hard magnetic material such as CoPt. First bias magnetic layer
13 is provided on seed layer 12 in order to ensure good magnetic
characteristics (high coercive force and squareness ratio). Seed layer 12
may be made of a Cr layer having a thickness of 3 nm, for example.

[0048]Insulating film 11 made of Al2O3 is provided between seed
layer 12 and MR stack 2. As shown in FIG. 2B, insulating film 11 extends
over the side of MR stack 2 which faces first bias magnetic layer 13 for
thereby preventing sense current 22 from flowing into first bias magnetic
layer 13.

[0049]Cap layer 14 made of Al2O3 is provided on first bias
magnetic layer 13 for preventing sense current 22 from flowing into first
bias magnetic layer 13. A Cr layer may be provided between cap layer 14
and first bias magnetic layer 13 for allowing first bias magnetic layer
13 to have good magnetic characteristics. Cap layer 14 may be made of a
non-magnetic metal layer.

[0051]Ferromagnetic layers 18a, 18b comprise respective soft magnetic
layers each made of 80Ni20Fe. Antiferromagnetic layers 19a, 19b comprise
respective IrMn layers, and are strongly exchange-coupled
antiferromagnetically to ferromagnetic layers 18a, 18b. Therefore,
ferromagnetic layers 18a, 18b have their magnetization directions secured
substantially parallel to track width direction T. The magnetization
direction of ferromagnetic layer 18a is substantially anti-parallel to
the magnetization direction of ferromagnetic layer 18b. In other words,
the magnetic pole on the surface of second bias magnetic layer 17a which
faces MR stack 2 has the same polarity as the magnetic pole on a surface
of the second bias magnetic layer 17b which faces the MR stack 2.

[0052]Antiferromagnetic layers 19a, 19b may comprise PtMn layers, NiMn
layers, or the like rather than the IrMn layers. Ferromagnetic layers
18a, 18b may comprise arbitrary soft magnetic layers which can strongly
be exchange-coupled to antiferromagnetic layers 19a, 19b, rather than the
NiFe layers.

[0053]Cap layers 16, which are made of Al2O3 and have a
thickness of about 5 nm, are provided respectively on second bias
magnetic layers 17a, 17b. Insulating films 15 and cap layers 16 serve to
prevent sense current 22 from flowing into bias magnetic layers 17a, 17b.

[0054]As shown in FIG. 2C, first bias magnetic layer 13 extends toward MR
stack 2 while a width thereof in track width direction T decreases.
Specifically, first bias magnetic layer 13 is in the shape of an
isosceles trapezoid within a plane parallel to the stacked layers, the
isosceles trapezoid having two sides parallel with the shorter side being
disposed closely to MR stack 2. The width of the shorter side
(hereinafter referred to as tip end width Wf is about the same as the
width of MR stack 2 in track width direction T. Therefore, the magnetic
fluxes in first bias magnetic layer 13 are gradually converged in the
isosceles trapezoid thereof, and are efficiently applied to MR stack 2.

[0055]The exterior angle α (hereinafter referred to as tip end angle
α) at both ends of the shorter side of the isosceles trapezoid is
of about 60 degrees (see FIG. 2C), for example.

[0056]Non-magnetic layers 20 are provided on the both sides of first bias
magnetic layer 13 in track width direction T. Non-magnetic layers 20 are
made of respective Cr layers, for example, and are provided to keep first
bias magnetic layer 13 and second bias magnetic layers 17a, 17b spaced
from each other. In other words, second bias magnetic layers 17a, 17b are
not disposed on both sides of first bias magnetic layer 13 in track width
direction T.

[0058]The magnetic pole on the surface of first bias magnetic layer 13
which faces MR stack 2 has a polarity different from the polarity of the
magnetic pole on surfaces of the second bias magnetic layers 17a, 17b
which face MR stack 2. FIG. 3 shows the directions of bias magnetic
fields from first and second bias magnetic layers 13, 17a, 17b. In FIG.
3, MR stack 2 and first and second bias magnetic layers 13, 17a, 17b are
schematically illustrated, and the arrows represent the directions of the
bias magnetic fields. In second bias magnetic layers 17a, 17b, the
magnetic fields extend toward MR stack 2. In MR stack 2, the magnetic
fields extend toward first bias magnetic layer 3, i.e., in a direction
substantially perpendicular to air bearing surface S. In first bias
magnetic layer 13, the magnetic field extends in direction Q
perpendicular to air bearing surface S. Accordingly, a strong bias
magnetic field which is substantially perpendicular to air bearing
surface S is applied to MR stack 2.

[0059]FIG. 4 is a conceptual view showing the operation principle of the
magneto-resistance effect element of the present embodiment. The abscissa
indicates magnitude of external magnetic field, and the ordinate
indicates signal output. In the figure, the magnetization direction of
upper magnetic layer 8 and the magnetization direction of lower magnetic
layer 6 are indicated by FL1 and FL2, respectively. When neither bias
magnetic fields emitted from first and second bias magnetic layer 13,
17a, 17b nor an external magnetic field emitted from recording medium 21
does not exist, the magnetization direction of upper magnetic layer 8 and
the magnetization direction of lower magnetic layer 6 are anti-parallel
to each other. However, since a bias magnetic field is applied actually,
the magnetization direction of upper magnetic layer 8 and the
magnetization direction of lower magnetic layer 6 are rotated from the
anti-parallel state toward a parallel state. Thus, the relative angle
formed between the magnetization direction of upper magnetic layer 8 and
the magnetization direction of lower magnetic layer 6 is about 90°
at an initial magnetization state (B in the figure). When an external
magnetic field is applied from recording medium 21 in this state, the
relative angle between the magnetization direction of upper magnetic
layer 8 and the magnetization direction of lower magnetic layer 6
increases (a state closer to the anti-parallel state) or decreases (a
state closer to the parallel state) in accordance with the direction of
the external magnetic field. If the state comes close to the
anti-parallel state, then electrons emitted from the electrode are apt to
be scattered, leading to an increase in electric resistance of sense
current 22 (see A in the figure). If the state comes close to the
parallel state, then electrons emitted from electrode are less apt to be
scattered, leading to a decrease in the electric resistance of sense
current 22 (see C in the figure). In this way, by utilizing the change in
the relative angle between the magnetization direction of upper magnetic
layer 8 and the magnetization direction of lower magnetic layer 6, an
external magnetic field can be detected.

[0060]In the present embodiment, as a result of adjusting the thickness,
the configuration, etc. of first and second bias magnetic layers 13, 17a,
17b, the magnetization direction of upper magnetic layer 8 and the
magnetization direction of lower magnetic layer 6 are approximately
perpendicular to each other in the initial magnetization state (B in FIG.
4). Because the magnetization directions are perpendicular to each other
in the initial magnetization state, a large change in output against a
change in an external magnetic field, and thus, a large change in
magnetic resistance can be obtained, and good asymmetry can also be
obtained. If the bias magnetic field is insufficient, then the initial
magnetization state becomes close to the anti-parallel state (A in FIG.
4), leading to low output and large asymmetry. Similarly, if the bias
magnetic field is excessive, then the initial magnetization state becomes
close to the parallel state (C in FIG. 4), leading to low output and
large asymmetry.

[0061]Magneto-resistance effect element 1 of the present embodiment
include not only first bias magnetic layer 13, but also second bias
magnetic layers 17a, 17b for applying bias magnetic field of sufficient
magnitude to upper and lower magnetic layers 8, 6.

[0063]FIGS. 6A and 6B show the magnetization directions of upper and lower
magnetic layers 8, 6 of a magneto-resistance effect element which has not
second bias magnetic layers 17a, 17b. Specifically, FIG. 6A shows the
magnetization direction of upper magnetic layer 8 when only the bias
magnetic field emitted from first bias magnetic layer 13 is applied, and
FIG. 6B shows the magnetization direction of lower magnetic layer 6 when
only the bias magnetic field emitted from first bias magnetic layer 13 is
applied. Bias magnetic field 44 is applied in direction Q perpendicular
to air bearing surface S. Therefore, magnetization directions 41, 42 of
upper magnetic layer 8 and lower magnetic layer 6 are rotated from track
width direction T. Magnetization directions 41, 42 of upper magnetic
layer 8 and lower magnetic layer 6 are substantially perpendicular to
each other. Since first bias magnetic layer 13 is provided on a side of
the MR stack 2 opposite to air bearing surface S, the intensity of bias
magnetic field 44 at air bearing surface S is relatively low. Therefore,
it is difficult for the magnetization directions of upper and lower
magnetic layers 8, 6 to extend perpendicularly to each other in a region
near air bearing surface S. Particularly, because upper and lower
magnetic layers 8, 6 that are near air bearing surface S tend to react
sharply to the external magnetic field emitted from recording medium 21,
it is necessary to maintain a necessary bias magnetic field near air
bearing surface S.

[0064]FIG. 7A shows the magnetization direction of upper magnetic layer 8
when the bias magnetic fields emitted from first and second bias magnetic
layers 13, 17a, 17b are applied, and FIG. 7B shows the magnetization
direction of lower magnetic layer 6 when the bias magnetic fields emitted
from first and second bias magnetic layers 13, 17a, 17b are applied.
According to the present embodiment, since second bias magnetic layers
17a, 17b are provided respectively on both sides of MR stack 2 in track
width direction T, strong bias magnetic field 44 is applied to wider
areas of upper and lower magnetic layers 8, 6 than in the case of the
magnetization directions shown in FIGS. 6A and 6B. Particularly, the
intensity of bias magnetic field 44 near air bearing surface S is
increased. Near the centers of upper and lower magnetic layers 8, 6, bias
magnetic field 44 has its direction Q substantially perpendicular to air
bearing surface S. As a result, the magnetization directions of upper and
lower magnetic layers 8, 6 are substantially perpendicular to each other
in wider areas than in the case of the magnetization directions shown in
FIGS. 6A and 6B. Thus, the detection sensitivity of magneto-resistance
effect element 1 is increased.

[0065]Magneto-resistance effect element 1 of the above embodiment which
includes first and second bias magnetic layers 13, 17a, 17b will be
referred to as Inventive Example, and the magneto-resistance effect
element which has not second bias magnetic layers 17a, 17b according to
the related art will be referred to as Comparative Example. The
performances of the magneto-resistance effect elements according to
Inventive Example and Comparative Example will be compared with each
other. The layer structures of MR stack 2 and first and second bias
magnetic layers 13, 17a, 17b according to the Inventive Example are
identical to those of the above embodiment (see Tables 1, 2).

[0066]The layer structure of the MR stack according to the Comparative
Example is identical to the layer structure of MR stack 2 according to
the Inventive Example. The magneto-resistance effect element of the
Comparative Example has an insulating film made of Al2O3 in
place of second bias magnetic layers 17a, 17b. The magneto-resistance
effect element of the Comparative Example also includes a CoPt film
having a film thickness of 30 nm disposed as a first bias magnetic layer
on an Al2O3 film having a film thickness of 5 nm and a Cr seed
layer having a film thickness of 5 nm, on the side of the MR stack (or
spin-valve film) which is opposite to the air bearing surface, as with
the Inventive Example. In both the Inventive Example and Comparative
Example, the width of the MR stack in track width direction T is 50 nm
and the height of the MR stack is 50 nm.

[0067]Table 3 shows detection characteristics of the magneto-resistance
effect elements according to the Inventive Example and Comparative
Example. In Table 3, the effective track width is defined as a half-value
width of a micro-track profile (an output profile produced by scanning a
micro-track that is sufficiently narrower than the track width, in the
track width direction).

[0068]In the Inventive Example and Comparative Example, the
magneto-resistance effect elements have a resistance of 20Ω and a
magneto-resistance ratio of 5%. However, the signal output of the
magneto-resistance effect element of the Inventive Example is higher than
the signal output of the magneto-resistance effect element of the
Comparative Example. This is because the perpendicularity of the
magnetization directions of upper and lower magnetic layers 8, 6 in the
initial magnetization state is improved. Consequently, the detection
sensitivity of magneto-resistance effect element 1 of the Inventive
Example is increased.

[0069]In the Inventive Example and Comparative Example, the optical track
widths are the same as each other. However, the effective track width
according to the Inventive Example is smaller than the effective track
width according to the Comparative Example. This is because second bias
magnetic layers 17a, 17b function as shields for shielding the magnetic
fields emitted from adjacent tracks.

[0070]A method of manufacturing above-mentioned magneto-resistance effect
element 1 will be described with reference to the flowchart of FIG. 8 and
FIGS. 9A to 17C. FIGS. 9A, 10A, . . . , 17A are cross-section views of a
wafer, taken along a surface forming a recording medium. FIGS. 9B, 10B, .
. . , 17B are cross-section views of the wafer, cut out in a direction
perpendicular to the surface forming the recording medium. FIGS. 9C, 10C,
. . . , 17C are top views of the wafer. Positions of the cross-sections
in FIGS. 9B, 10B, . . . , 17B are shown in FIGS. 9A, 10A, . . . , 17A,
respectively.

[0072](Step S2) Next, both sides of MR stack 2 in track width direction T
are removed, and then the removed spaces are filled again with respective
second bias magnetic layers 17a, 17b (second bias magnetic layer forming
step). Specifically, as shown in FIGS. 10A to 10C, resist 31 is deposited
on MR stack 2 and then formed into a predetermined shape. Using shaped
resist 31 as a mask, the both sides of MR stack 2 in track width
direction T are removed.

[0073]Thereafter, as shown in FIGS. 11A to 11C, insulating film 15 of
Al2O3, magnetic layer 17 which is to become second bias
magnetic layers, and cap layer 16 of Al2O3 are successively
deposited on resist 31 and lower shield electrode layer 4. Magnetic layer
17 includes a ferromagnetic layer and an antiferromagnetic layer.

[0074]Further, as shown in FIGS. 12A to 12C, resist 31 is removed by the
lift-off process together with insulating film 15, magnetic layer 17 and
cap layer 16 which are deposited over resist 31. Magnetic layer 17 that
is left on the both sides of MR stack 2 in track width direction T serves
as second bias magnetic layers 17a, 17b.

[0075]Cap layer 16 should preferably be planarized to a level lying flush
with the upper surface of MR stack 2. Cap layer 16 should be planarized
for the purposes of planarizing upper shield layer 3 to be formed in a
subsequent step and removing burrs formed when resist 31 and other layers
are lifted off. Cap layer 16 may be planarized by chemical mechanical
polishing (CMP), for example.

[0076](Step S3) Next, portions of MR stack 2, cap layer 16, and second
bias magnetic layers 17a, 17b on the side opposite to a plane S' which is
to become the air bearing surface are removed, and the removed space is
filled with non-magnetic layer 20 (non-magnetic layer forming step).
Specifically, as shown in FIGS. 13A to 13C, resist 34 is deposited on MR
stack 2 and cap layer 16 and then formed into a predetermined shape.
Using shaped resist 34 as a mask, the portions of MR stack 2, cap layer
16, and second bias magnetic layers 17a, 17b are removed.

[0077]Thereafter, as shown in FIGS. 14A to 14C, insulating film 35,
non-magnetic layer 20 made of Cr, and cap layer 36 are successively
deposited on resist 34 and lower shield electrode layer 4. Then, resist
34 is removed by the lift-off process. After the removal of resist 34,
burrs are removed by CMP to provide a flat surface.

[0078](Step S4) Next, portions of non-magnetic layer 20 and cap layer 36
are removed, and the removed space is filled with first bias magnetic
layer 13 (first bias magnetic layer forming step). Specifically, as shown
in FIGS. 15A to 15C, resist 32 is deposited on cap layer 36 and then
formed into a predetermined shape. Using shaped resist 32 as a mask, the
portions of non-magnetic layer 20 and cap layer 36 are removed, forming a
recess 33.

[0079]Recess 33 extends toward MR stack 2 while a width thereof in track
width direction T decreases. As shown in FIG. 15C, recess 33 is in the
shape of an isosceles trapezoid as viewed from above. In the actual
fabrication process, recess 33 does not need to be strictly in the shape
of an isosceles trapezoid, but may be of a general trapezoidal shape or
may have round corners. Since first bias magnetic layer 13 will be formed
in recess 33 as described later, a portion of lower shield electrode 4
may be removed by means of milling if there is a need to ensure the
thickness of first bias magnetic layer 13.

[0080]Thereafter, as shown in FIGS. 16A to 16C, insulating film 11, seed
layer 12, first bias magnetic layer 13, and cap layer 14 are deposited in
recess 33 (seed layer 12 is omitted from illustration). Insulating film
11 and seed layer 12 are formed by ion beam sputtering. In order to make
insulating film 11 electrically insulative, insulating film 11 is held in
reliable contact with the side wall of MR stack 2. Low-temperature CVD
(chemical vapor deposition), rather than ion beam sputtering, may be
employed to form insulating film 11 and seed layer 12.

[0081]Thereafter, resist 32 is removed by lift-off process. After the
removal of resist 32, burrs are removed by CMP to provide a flat surface.

[0082](Step S5) Then, the magnetization directions of ferromagnetic layers
18a, 18b of second bias magnetic layers 17a, 17b are secured
(magnetization direction securing step). Specifically, the assembly is
heated to a temperature equal to or higher than the blocking temperature
of antiferromagnetic layers 19a, 19b, and then annealed. At this time,
the magnetization directions of ferromagnetic layers 18a, 18b are secured
by the magnetic field emitted from first bias magnetic layer 13. Since
tip end width Wf of first bias magnetic layer 13 is small, the magnetic
field emitted from first bias magnetic layer 13 lies substantially
parallel to track width direction T within second bias magnetic layers
17a, 17b. Therefore, the magnetization directions of ferromagnetic layers
18a, 18b extend substantially parallel to track width direction T. The
magnetization directions of ferromagnetic layers 18a, 18b of second bias
magnetic layers 17a, 17b are substantially anti-parallel to each other.
The magnetic pole on the surface of second bias magnetic layer 17a which
faces MR stack 2 and the magnetic pole on the surface of second bias
magnetic layer 17b which faces MR stack 2 are of the same polarity. The
magnetic pole on the surface of first bias magnetic layer 13 which faces
MR stack 2 and the magnetic poles on the surfaces of second bias magnetic
layers 17a, 17b which face MR stack 2 are different from each other.

[0083](Step S6) Next, as shown in FIGS. 17A to 17C, upper shield electrode
layer 3 is formed on MR stack 2 and cap layers 14, 16, 36 (upper shield
electrode layer forming step). Specifically, an electrode film (not
shown) is formed to a film thickness of about 50 nm by sputtering, and
then upper shield electrode layer 3 is formed on the electrode film by
plating process.

[0084]Thereafter, a write head portion is formed, the wafer is then diced
into bars, and the air bearing surface is formed by polishing. Further,
each bar is separated into sliders, and the sliders are completed after
undergoing processes, such as cleaning and inspections.

[0085]The effect which the shape of first bias magnetic layer 13 has on
the signal output has been analyzed. MR stack 2 and second bias magnetic
layers 17a, 17b of magneto-resistance effect element 1 that has been
analyzed are of the layer structure shown in Tables 1, 2.

[0086]FIG. 18 is a graph showing the relationship between tip end width Wf
of first bias magnetic 13 layer and the signal output of
magneto-resistance effect element 1 at the time the magnetic field is
detected. The horizontal axis of the graph represents values produced by
dividing tip end width Wf of first bias magnetic 13 layer by the width
(hereinafter referred to as element width W, see FIGS. 2A, 2C) of MR
stack 2 in track width direction T. First bias magnetic layer 13 used for
the measurement of the signal output has a hexagonal shape including an
isosceles trapezoid as shown in FIG. 20A. First bias magnetic layer 13
has a width (hereinafter referred to as rear end width Wb) of 250 nm on
its side opposite to air bearing surface S, and a tip end angle α
of 60 degrees.

[0087]The signal output is of a substantially constant value of about 1.0
mV if tip end width Wf is in a range which is three times element width W
or greater. The signal output increases as tip end width Wf decreases.
The signal output sharply changes when tip end width Wf is about twice
element width W. The signal output is maximum when tip end width Wf is
essentially the same as element width W.

[0088]When tip end width Wf is large, the magnetic field emitted from
first bias magnetic layer 13 is applied to second bias magnetic layers
17a, 17b in direction Q perpendicular to air bearing surface S.
Therefore, the magnetization directions of second bias magnetic layers
17a, 17b are perpendicularly inclined to air bearing surface S, failing
to apply a bias magnetic field in an appropriate direction to upper and
lower magnetic layers 8, 6. For these reasons, the signal output is
decreases when tip end width Wf is large.

[0089]Therefore, tip end width Wf should preferably be equal to or smaller
than twice element width W, and more preferably be substantially equal to
element width W.

[0090]FIG. 19 is a graph showing the relationship between tip end angle
α of first bias magnetic layer 13 and the signal output of
magneto-resistance effect element 1. FIGS. 20A, 20B show
magneto-resistance effect element 1 used to measure the signal output
shown in FIG. 19. Specifically, FIGS. 20A, 20B are cross-sectional views
taken along a plane parallel to the film surface of MR stack 2, i.e.,
along the x-y plane in FIG. 1.

[0091]First bias magnetic layer 13 has a length of 500 nm in direction Q
perpendicular to air bearing surface S, and has tip end width Wf having a
thickness of 50 nm. If tip end angle α of first bias magnetic layer
13 is large, then first bias magnetic layer 13 is in the shape of an
isosceles trapezoid as shown in FIG. 20B, and first bias magnetic layer
13 has tip end width Wf that has a thickness of 250 nm or less.

[0092]If tip end angle α of first bias magnetic layer 13 is small,
then the width of first bias magnetic layer 13 is progressively larger
away from MR stack 2 until the width reaches 250 nm (see FIG. 20A). In
other words, first bias magnetic layer 13 has a hexagonal shape including
an isosceles trapezoid.

[0093]If tip end angle α of first bias magnetic layer 13 is nil,
then first bias magnetic layer 13 is in the shape of a rectangle having
tip end width Wf that is 250 nm thick. If tip end angle α of first
bias magnetic layer 13 is 90 degrees, then first bias magnetic layer 13
is in the shape of a rectangle having tip end width Wf that is 500 nm
thick.

[0094]If tip end angle α of first bias magnetic layer 13 is nil,
then magneto-resistance effect element 1 produces a signal output of
about 1.0 mV. If tip end angle α is within a range from 0 degree to
about 60 degrees, the signal output of magneto-resistance effect element
1 increases as tip end angle α increases. Then the signal output of
magneto-resistance effect element 1 is maximum at tip end angle α
that is about 60 degrees. If tip end angle α is within a range from
about 60 degrees to 90 degrees, the signal output of magneto-resistance
effect element 1 decreases as tip end angle α increases.

[0095]If tip end angle α is within a range from 40 degrees to 80
degrees, the signal output of magneto-resistance effect element 1 is at
least 5% greater than if tip end angle α is nil. Therefore, tip end
angle α should preferably be kept in the range from 40 degrees to
80 degrees, and more preferably be about 60 degrees.

[0096]The magneto-resistance effect element according to the present
invention has been described in detail above. However, the present
invention is not limited to the above embodiment and Inventive Example,
but may be modified within the scope thereof. For example, second bias
magnetic layers 17a, 17b may comprise respective antiferromagnetic layers
19a, 19b and respective ferromagnetic layers 18a, 18b disposed on
respective antiferromagnetic layers 19a, 19b. The first bias magnetic
layer does not need to be strictly trapezoidal in shape.

[0097]The following describes a thin film magnetic head in which the
above-described magneto-resistance effect element has been used. FIG. 21
is a cross-sectional diagram through the thin film magnetic head in a
direction perpendicular to air bearing surface S. As shown in FIG. 21,
thin film magnetic head 320 includes slider 210 which is mainly composed
of ALTIC (AL2O3--TiC), and magnetic head part 330. Magnetic
head part 330 is provided on side surface 2102 of slider 210. Magnetic
head part 330 includes magneto-resistance effect element 1 as a
reproducing element and electromagnetic coil device 339 as an
inductive-type electromagnetic conversion device.

[0098]The layers of MR stack 2 which forms magneto-resistance effect
element 1 are provided to be substantially parallel to a side surface of
slider 210, and lower shield electrode layer 4 is arranged to be closer
to slider 210 than upper shield electrode layer 3. Upper and lower shield
electrode layers 3 and 4 and MR stack 2 form a portion of air bearing
surface S.

[0101]Electromagnetic coil device 339 is preferably a perpendicular
magnetic recording-use coil. Electromagnetic coil device 339 includes
main magnetic pole layer 340, gap layer 341a, coil insulating layer 341b,
coil layer 342, and auxiliary magnetic pole layer 344. Main magnetic pole
layer 340 leads magnetic flux induced by coil layer 342 to a recording
layer of magnetic recording medium 21. Here, it is preferable that a
width in the track--with direction (X-direction in the drawings) and a
thickness in the layer direction (Z-direction in the drawings) of the end
portion of main magnetic pole layer 340 on air bearing surface S side are
smaller than at other portions of main magnetic pole layer 340. Such an
arrangement allows generation of a fine ferromagnetic field for
supporting a high recording density.

[0102]The end portion of auxiliary magnetic pole layer 344 on air bearing
surface S side which is magnetically coupled to main magnetic pole layer
340 forms a trailing shield part having a cross-sectional surface which
is wider than other portions of auxiliary magnetic pole layer 344.
Auxiliary magnetic pole layer 344 faces the end portion of main magnetic
pole layer 340 on air bearing surface S side via gap layer 341a and coil
insulating layer 341b. Gap layer 341a and coil insulating layer 341b are
formed using an insulator such as alumina. By providing auxiliary
magnetic pole layer 344, the magnetic field gradient between auxiliary
magnetic pole layer 344 and main magnetic pole layer 340 in the region of
air bearing surface S is increased. As a result, jitter in the signal
output is reduced, and the error rate during reading is reduced.

[0103]The thickness of auxiliary magnetic pole layer 344 is approximately
0.5 to 5 μm, and is constructed from an alloy composed of two or three
materials selected from Ni, Fe, and Co, an alloy mainly composed of these
materials with other elements added, or the like. Auxiliary magnetic pole
layer 344 is formed using, for instance, a frame plating method or a
sputtering method.

[0104]Gap layer 341a is formed between coil layer 342 and main magnetic
pole layer 340, and is composed of Al2O3, DLC (Diamond-Like
Carbon) or the like, at a thickness of 0.01 to approximately 0.5 μm.
To form gap layer 341a, a sputtering method, a CVD method, or the like
may be used.

[0105]Coil layer 342 is, for instance, formed from Cu or the like at a
thickness of approximately 0.5 to approximately 3 μm. To form coil
layer 342, a frame plating method or the like may be used. A rear end of
main magnetic pole layer 340 is joined to a portion, of auxiliary
magnetic pole layer 344, that is positioned away from air bearing surface
S. Coil layer 342 is formed so as to surround this joint portion.

[0106]A coil insulating layer 341b composed of an insulator, such as a
cured aluminum oxide or a resist layer, at a thickness of 0.1 to
approximately 5 μm is formed between coil layer 342 and auxiliary
magnetic pole layer 344. Insulating layer 338 is formed so as to cover
electromagnetic coil device 339 on an opposite side of electromagnetic
coil device 339 to the side of slider 210.

[0107]Next, explanation will be made regarding a wafer for fabricating a
magnetic field detecting element described above. FIG. 22 is a schematic
plan view of a wafer. Wafer 100 has a MR stack which is deposited thereon
to form at least magneto-resistance effect element. Wafer 100 is diced
into bars 101 which serve as working units in the process of forming air
bearing surface ABS. After lapping, bar 101 is diced into sliders 210
which include thin-film magnetic heads. Dicing portions, not shown, are
provided in wafer 100 in order to dice wafer 100 into bars 101 and into
sliders 210.

[0108]Referring to FIG. 23, slider 210 has a substantially hexahedral
shape. One of the six surfaces of slider 210 forms an air bearing surface
ABS, which is positioned opposite to the hard disk.

[0109]Referring to FIG. 24, head gimbal assembly 220 has slider 210 and
suspension 221 for resiliently supporting slider 210. Suspension 221 has
load beam 222 in the shape of a flat spring and made of, for example,
stainless steel, flexure 223 that is attached to one end of load beam
222, and base plate 224 provided on the other end of load beam 222.
Slider 210 is fixed to flexure 223 to provide slider 210 with an
appropriate degree of freedom. The portion of flexure 223 to which slider
210 is attached has a gimbal section for maintaining slider 210 in a
fixed orientation.

[0110]Slider 210 is arranged opposite to hard disk 262, which is a
rotationally-driven disc-shaped storage medium, in a hard disk drive.
When hard disk 262 rotates in the z direction shown in FIG. 24, airflow
which passes between hard disk 262 and slider 210 creates a dynamic lift,
which is applied to slider 210 downward in the y direction. Slider 210 is
configured to lift up from the surface of hard disk 262 due to this
dynamic lift effect. Magneto-resistance effect element 1 is formed in
proximity to the trailing edge (the end portion at the lower left in FIG.
23) of slider 210, which is on the outlet side of the airflow.

[0111]The arrangement in which head gimbal assembly 220 is attached to arm
230 is called head arm assembly 221. Arm 230 moves slider 210 in
transverse direction x with regard to the track of hard disk 262. One end
of arm 230 is attached to base plate 224. Coil 231, which constitutes a
part of a voice coil motor, is attached to the other end of arm 230.
Bearing section 233 is provided in the intermediate portion of arm 230.
Arm 230 is rotatably held by shaft 234 which is attached to bearing
section 233. Arm 230 and the voice coil motor to drive arm 230 constitute
an actuator.

[0112]Referring to FIG. 25 and FIG. 26, a head stack assembly and a hard
disk drive that incorporate the slider mentioned above will be explained
next. The arrangement in which head gimbal assemblies 220 are attached to
the respective arm of a carriage having a plurality of arms is called a
head stack assembly. FIG. 25 is a side view of a head stack assembly, and
FIG. 26 is a plan view of a hard disk drive. Head stack assembly 250 has
carriage 251 provided with a plurality of arms 252. Head gimbal
assemblies 220 are attached to arms 252 such that head gimbal assemblies
220 are arranged apart from each other in the vertical direction. Coil
253, which constitutes a part of the voice coil motor, is attached to
carriage 251 on the side opposite to arms 252. The voice coil motor has
permanent magnets 263 which are arranged in positions that are opposite
to each other and interpose coil 253 therebetween.

[0113]Referring to FIG. 26, head stack assembly 250 is installed in a hard
disk drive. The hard disk drive has a plurality of hard disks which are
connected to spindle motor 261. Two sliders 210 are provided per each
hard disk 262 at positions which are opposite to each other and interpose
hard disk 262 therebetween. Head stack assembly 250 and the actuator,
except for sliders 210, work as a positioning device in the present
invention. They carry sliders 210 and work to position sliders 210
relative to hard disks 262. Sliders 210 are moved by the actuator in the
transverse direction with regard to the tracks of hard disks 262, and
positioned relative to hard disks 262. Magneto-resistance effect element
1 that is included in slider 210 writes information to hard disk 262 by
means of the write head portion, and reads information recorded in hard
disk 262 by means of the read head portion.

[0114]Although certain preferred embodiments of the present invention have
been shown and described in detail, it should be understood that various
changes and modifications may be made without departing from the spirit
or scope of the appended claims.